Circuit breaker with independent trip and reset lockout

ABSTRACT

Resettable circuit breakers having an independent trip mechanism and a reset lockout are provided. The trip mechanism operates independently of the fault protection operations, and the reset lockout prevents the resetting of the circuit breaker if the fault protection is non-operational or if an open neutral condition exists.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/379,140filed Aug. 20, 1999, which issued on Sep. 11, 2001 as U.S. Pat. No.6,288,882 which is a continuation-in-part of Ser. No. 09/369,759, filedAug. 6, 1999, now U.S. Pat. No. 6,282,070 which is acontinuation-in-part of application Ser. No. 09/138,955, filed Aug. 24,1998, which issued on Mar. 21, 2000 as U.S. Pat. No. 6,040,967 all ofwhich are incorporated herein in their entirety by reference.

BACKGROUND

1. Field

The present application relates to a family of resettable circuitbreakers that include a reset lockout operation and optionally anindependent trip operation, and to power distribution systems in whichsuch circuit breakers are utilized. More particularly, the presentapplication is directed to circuit breakers that include a reset lockout capable of preventing the circuit breaker from resetting if acircuit interrupting portion used for fault protection is notfunctioning properly and/or if an open neutral condition exists. Inaddition, a trip portion may be added to the circuit breaker to permitthe breaker to be tripped independent of the operation of the circuitinterrupting portion.

2. Description of the Related Art

The electrical wiring device industry has witnessed an increasing callfor circuit interrupting devices or systems which are designed tointerrupt power to various loads, such as household appliances, consumerelectrical products and branch circuits. In particular, electrical codesrequire electrical circuits in home bathrooms and kitchens to beequipped with ground fault circuit protection. Presently available GFCIdevices, such as the GFCI receptacle described in commonly owned U.S.Pat. No. 4,595,894, use an electrically activated trip mechanism tomechanically break an electrical connection between one or more inputand output conductors. Such devices are resettable after they aretripped by, for example, the detection of a ground fault. In the devicediscussed in the '894 patent, the trip mechanism used to cause themechanical breaking of the circuit (i.e., the connection between inputand output conductors) includes a solenoid (or trip coil). A test buttonis used to test the trip mechanism and circuitry used to sense faults,and a reset button is used to reset the electrical connection betweeninput and output conductors.

However, instances may arise where an abnormal condition, caused by forexample a lightning strike, occurs which may result not only in a surgeof electricity at the device and a tripping of the device but also adisabling of the trip mechanism used to cause the breaking of thecircuit. This may occur without the knowledge of the user. Under suchcircumstances, an unknowing user faced with a GFCI which has tripped maypress the reset button which, in turn, will cause the device with aninoperative trip mechanism to reset without the ground fault protectionavailable.

Further, an open neutral condition, which is defined in UnderwritersLaboratories (UL) Standard PAG 943A, may exist with the electrical wiressupplying electrical power to such GFCI devices. If an open neutralcondition exists with the neutral wire on the line (versus load) side ofthe GFCI device, an instance may arise where a current path is createdfrom the phase (or hot) wire supplying power to the GFCI device throughthe load side of the device and a person to ground. In the event that anopen neutral condition exists, current GFCI devices which have tripped,may be reset even though the open neutral condition may remain.

Commonly owned application Ser. No. 09/138,955, filed Aug. 24, 1998,which is incorporated herein in its entirety by reference, describes afamily of resettable circuit interrupting devices capable of locking outthe reset portion of the device if the circuit interrupting portion isnon-operational or if an open neutral condition exists. Commonly ownedapplication Ser. No. 09/175,228, filed Oct. 20, 1998, which isincorporated herein in its entirety by reference, describes a family ofresettable circuit interrupting devices capable of locking out the resetportion of the device if the circuit interrupting portion isnon-operational or if an open neutral condition exists and capable ofbreaking electrical conductive paths independent of the operation of thecircuit interrupting portion.

Current resettable circuit breakers with fault protection capabilities,such as the HOM-GFI series of GFCI circuit breakers manufactured bySquare-D Company, Palatine, Ill., have line and load power and neutralconnections and a switch for controlling power distribution to a load.To provide fault protection, such circuit breakers have sense circuitryand linkage to the switch, which are capable of sensing faults (e.g.,ground faults) between the load power and the line neutral conductorsand opening the switch. A test button accessible from an exterior of thebreaker is used to test the operation of the fault protection portion ofthe breaker when depressed. However, like conventional resettablereceptacles, conventional resettable circuit breakers do not includeeither a reset lockout or an independent trip portion.

SUMMARY

The present application relates to a family of resettable circuitbreakers having fault protection capabilities. The circuit breakersaccording to the present application include a circuit interruptingportion, a reset portion and a reset lockout portion. The circuitbreakers may also include an independent trip portion. The reset lockoutportion inhibits the resetting of the circuit breaker if the circuitinterrupting portion is non-operational or if an open neutral conditionexists. The trip portion operates independently of the circuitinterrupting portion and facilitates tripping of the circuit breakerwhether or not the circuit interrupting portion is operating properly.

In one embodiment, a GFCI circuit breaker having a housing, a circuitinterrupting portion, a reset portion and a reset lockout portion isprovided. Preferably, the housing has line phase and load phaseconnections that are accessible from an exterior of the housing and aconductive path within the housing between the line and load phaseconnections. The circuit interrupting portion is disposed within thehousing and is configured to open the conductive path upon theoccurrence of a ground fault. Examples of faults contemplated includeground faults, arc faults, immersion detection faults, appliance leakagefaults and equipment leakage faults. The reset portion includes anactuator that is also accessible from the exterior of the housing, andis configured to close the conductive path upon actuation. Preferably,the reset lockout portion inhibits the closing of the conductive path ifthe circuit interrupting portion is non-operational or if an openneutral condition exists. The reset lockout portion may be an activetype lockout that prevents the resetting of the conductive path, or apassive type lockout whose characteristics inherently inhibit theresetting of the conductive path.

The circuit breaker may optionally include a trip portion disposed atleast partially within the housing. The trip portion is configured toopen the conductive path independently of the operation of the circuitinterrupting portion. Thus, in this configuration, if the circuitinterrupting portion is not operating properly, the circuit breaker canstill be tripped but it cannot be reset, since the reset operationutilizes the circuit interrupting portion when resetting the breaker.

The present application also provides a method for testing the operationof a circuit breaker having a housing with line and load phaseconnections accessible from an exterior surface of the housing, and aconductive path between the line and load phase connections. The methodincludes the steps of: 1) manually activating a trip portion of thecircuit breaker to open the conductive path and to enable a resetlockout portion that inhibits closing the conductive path; and 2)activating a reset portion to perform a reset operation. During thereset operation a circuit interrupting portion is activated, and if thecircuit interrupting portion is operational the circuit interruptingportion disables the reset lockout portion and facilitates closing ofthe conductive path. If, however, the circuit interrupting portion isnot operating properly, the reset lockout portion remains enabled sothat closing the conductive path is inhibited.

The present application also provides a circuit interrupting system thatincludes a source of power, a circuit breaker, having for example theabove described independent trip and reset lockout portions, connectedto the source of power, and at least one load connected to the circuitbreaker.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present application are described hereinwith reference to the drawings in which similar elements are givensimilar reference characters, wherein:

FIG. 1 is a perspective view of an exemplary ground fault circuitinterrupting device according to the present application;

FIG. 2 is side elevational view, partly in section, of components of anindependent trip mechanism and a reset mechanism for the GFCI deviceshown in FIG. 1, illustrating the components when the circuitinterrupting device is in a set or circuit making position;

FIG. 3 is a side elevational view similar to FIG. 2, illustratingcomponents of the independent trip mechanism when the circuitinterrupting device is in a circuit breaking position;

FIG. 4 is a side elevational view similar to FIG. 2, illustrating thecomponents of the reset mechanism during reset operation of the circuitinterrupting device;

FIGS. 5-7 are schematic representations of one embodiment of the resetmechanism of the present application, illustrating a latching memberused to make an electrical connection between input and outputconductors and to relate the reset mechanism with the operation of thecircuit interrupter;

FIG. 8 is a schematic diagram of a circuit for detecting ground faultsand resetting the circuit interrupting device of FIG. 1;

FIG. 9 is side elevational view, partly in section, of components of analternative embodiment of the independent trip mechanism, illustratingthe components when the circuit interrupting device is in a set orcircuit making position;

FIG. 10 is a side elevational view similar to FIG. 9, illustratingcomponents of the alternative independent trip mechanism when thecircuit interrupting device is in a circuit breaking position; and

FIG. 11 is a block diagram of a circuit interrupting system according tothe present application that incorporates a ground fault circuitinterrupter receptacle;

FIG. 12 is a perspective view of an exemplary ground fault circuitinterrupting circuit breaker according to the present application;

FIG. 13 is a cross-sectional view of the GFCI circuit breaker of FIG.12, taken along line I—I, illustrating the breaker in an ‘on’ state;

FIG. 14 is a cross sectional view of the GFCI circuit breaker of FIG. 12similar to FIG. 13 and illustrating the breaker in a ‘tripped’ state;

FIG. 15 is a cross sectional view of the GFCI circuit breaker of FIG. 12similar to FIG. 13 and illustrating the breaker with the reset lockoutin a lockout position;

FIG. 16 is a cross sectional view of the GFCI circuit breaker of FIG. 12similar to FIG. 15 and illustrating the reset lockout removed from thelockout position;

FIG. 17 is a cross sectional view of the GFCI circuit breaker of FIG. 12similar to FIG. 13 and illustrating the breaker in an ‘off’ state;

FIG. 18 is a cross sectional view of the GFCI circuit breaker of FIG. 12similar to FIG. 13 and illustrating partial activation of theindependent trip portion of the breaker;

FIGS. 19 and 20 are circuit diagrams for various embodiments of thesensing circuitry used to sense ground faults and switchingconfigurations for a reset enable switch assembly used when resettingthe circuit breaker;

FIG. 21 is another alternative switching configuration for the resetenable switch assembly used when resetting the circuit breaker;

FIG. 22 is a block diagram for the fault sensing circuitry for detectingarc faults;

FIG. 23 is a schematic diagram of the monitoring/interrupting circuitryfor the fault sensing circuitry of FIG. 22;

FIG. 24 is a schematic diagram of the processing circuitry for the faultsensing circuitry of FIG. 22;

FIG. 25 is schematic diagram of the monitoring/interrupting circuitryfor a circuit breaker with combined fault detection capabilities,illustrating circuitry capable of monitoring ground faults and circuitrycapable of monitoring arc faults;

FIG. 26 is a block diagram for the fault sensing circuitry for detectingmultiple types of faults;

FIG. 27 is schematic diagram of the monitoring/interrupting circuitryfor a circuit breaker with combined fault detection capabilities,illustrating circuitry capable of monitoring ground faults and circuitrycapable of monitoring arc faults at both the line side and the loadside;

FIG. 28 is a schematic diagram of the processing circuitry for detectingarc faults on the line side of the fault sensing circuitry of FIG. 26;

FIG. 29 is a schematic diagram of the processing circuitry for detectingarc faults on the load side of the fault sensing circuitry of FIG. 26;

FIG. 30 is a schematic diagram for the arc fault trigger generator forthe fault sensing circuitry of FIG. 26;

FIG. 31 is a schematic diagram of an alternative embodiment for the SCRtrigger circuit; and

FIG. 32 is a block diagram of an exemplary circuit interrupting systemfor home power distribution system incorporating a GFCI circuit breakerhaving a reset lockout operation according to the present application.

DETAILED DESCRIPTION

Resettable Circuit Interrupting Devices

The present application relates to a family of resettable circuitinterrupting devices for breaking and making electrical connectionsbetween input and output conductive paths associated with the devicesand to systems incorporating such devices. The family of devicesinclude: ground fault circuit interrupters (GFCI's), arc fault circuitinterrupters (AFCI's), immersion detection circuit interrupters(IDCI's), appliance leakage circuit interrupters (ALCI's) and equipmentleakage circuit interrupters (ELCI's). Generally, each circuitinterrupting device according to the present application has a circuitinterrupting portion, a reset portion and reset lockout portion, and anoptional trip portion, which will be described in more detail below.

The circuit interrupting and reset portions preferably useelectromechanical components to break and make the conductive pathbetween input and output conductors. More particularly, the circuitinterrupting portion is used to break electrical continuity betweeninput and output conductive paths (or conductors) upon the detection ofa fault. Operation of the reset and reset lockout portions is inconjunction with the operation of the circuit interrupting portion, sothat the electrical connection between conductive paths cannot be resetif the circuit interrupting portion is non-operational and/or if an openneutral condition exists.

The trip portion preferably operates independently of the circuitinterrupting portion so that in the event the circuit interruptingportion becomes non-operational the device can still be tripped.Preferably, the trip portion is manually activated and uses mechanicalcomponents to break the electrical connections. However, the tripportion may use electrical circuitry and/or electromechanical componentsto break the electrical connections.

For the purpose of the present application, the structure or mechanisms,used in the circuit interrupting devices, shown in the drawings anddescribed hereinbelow are incorporated into GFCI receptacles suitablefor installation in a single-gang junction box in a home, and GFCIcircuit breakers suitable for installation in a circuit breaker panel.However, the mechanisms according to the present application can beincluded in any of the various devices in the family of resettablecircuit interrupting devices.

Turning now to FIG. 1, an exemplary GFCI receptacle is shown. The GFCIreceptacle 10 has a housing 12 consisting of a relatively central body14 to which a face or cover portion 16 and a rear portion 18 areremovably secured. The face portion 16 has entry ports 20 for receivingnormal or polarized prongs of a male plug of the type normally found atthe end of a lamp or appliance cord set (not shown), as well asground-prong-receiving openings 22 to accommodate a three-wire plug. Thereceptacle also includes a mounting strap 24 used to fasten thereceptacle to a junction box.

A trip actuator 26, preferably a button, which is part of the tripportion to be described in more detail below, extends through opening 28in the face portion 16 of the housing 12. The trip actuator is used, inthis exemplary embodiment, to mechanically trip the GFCI receptacle,i.e., break the electrical connection between input and outputconductive paths, independent of the operation of the circuitinterrupting portion.

A reset actuator 30, preferably a button, which is part of the resetportion, extends through opening 32 in the face portion 16 of thehousing 12. The reset button is used to activate the reset operation,which re-establishes electrical continuity between the input and outputconductive paths, i.e., resets the device, if the circuit interruptingportion is operational.

Electrical connections to existing household electrical wiring are madevia binding screws 34 and 36, where screw 34 is an input (or line)connection point and screw 36 is an output (or load) connection point.It should be noted that two additional binding screws (not shown) arelocated on the opposite side of the receptacle 10. Similar to bindingscrews 34 and 36, these additional binding screws provide input andoutput connection points. Further, the input connections are for lineside phase (hot) and neutral conductors of the household wiring, and theoutput connections are for load side phase (hot) and neutral conductorsof the household wiring. The plug connections are also considered outputconductors. A more detailed description of a GFCI receptacle is providedin U.S. Pat. No. 4,595,894 which is incorporated herein in its entiretyby reference. It should also be noted that binding screws 34 and 36 areexemplary of the types of wiring terminals that can be used to providethe electrical connections. Examples of other types of wiring terminalsinclude set screws, pressure clamps, pressure plates, push-in typeconnections, pigtails and quick-connect tabs.

Referring to FIG. 2, the conductive path between the input connectionpoint 34 and the output connection point 36 (or the entry ports 20)includes contact arm 70 which is movable between stressed and unstressedpositions, movable contact 72, fixed contact 74 and contact arm 76. Amovable latching member 60 and contacts 72 and 74 are used to make andbreak the conductive path.

There is also shown in FIG. 2, mechanical components used during circuitinterrupting and device reset operations according to one embodiment ofthe present application. Although these components shown in the drawingsare electromechanical in nature, the present application alsocontemplates using semiconductor type circuit interrupting and resetcomponents, as well as other mechanisms capable or making and breakingelectrical continuity.

The circuit interrupting portion has a circuit interrupter andelectronic circuitry capable of sensing faults, e.g., currentimbalances, on the hot and/or neutral conductors. In a preferredembodiment for the GFCI receptacle, the circuit interrupter includes acoil assembly 50, a plunger 52 responsive to the energizing andde-energizing of the coil assembly and a banger 54 connected to theplunger 52. The banger 54 has a pair of banger dogs 56 and 58 whichinteract with movable latching member 60 used to set and reset theconnection between input and output conductors. The coil assembly 50 isactivated in response to the sensing of a ground fault by, for example,the sense circuitry shown in FIG. 8. FIG. 8 shows conventional circuitryfor detecting ground faults that includes a differential transformerthat senses current imbalances.

The reset portion includes reset button 30, movable latching member 60connected to the reset button 30, latching finger 64 and reset contacts62 and 63 that temporarily activate the circuit interrupting portionwhen the reset button is depressed. Preferably, the reset contacts 62and 63 are normally open momentary contacts. The latching finger 64 isused to engage side R of the contact arm 70 and move the arm 70 back toits stressed position where contact 72 touches contact 74.

The movable latching member 60 is, in this embodiment, common to eachportion (i.e., the trip, circuit interrupting, reset and reset lockoutportions) and used to facilitate making, breaking or locking out of theelectrical connections between the input and output conductive paths.However, the circuit interrupting devices according to the presentapplication also contemplate embodiments where there is no commonmechanism or member between each portion or between certain portions.

In the embodiment shown in FIGS. 2 and 3, the reset lockout portionincludes latching finger 64 which after the device is tripped, engagesside L of the movable arm 70 and blocks the movable arm 70 from movingso that contacts 72 and 74 are prevented from touching. In thisembodiment, latching finger 64 acts as an active inhibitor that preventsthe contacts from touching. Alternatively, the natural bias of movablearm 70 can be used as a passive inhibitor that prevents contacts 72 and74 from touching.

Referring now to FIGS. 2-4, the mechanical components of the circuitinterrupter and reset mechanisms in various stages of operation areshown. In FIG. 2, the GFCI receptacle is shown in a set position wheremovable contact arm 70 is in a stressed condition so that movablecontact 72 is in electrical engagement with fixed contact 74 of contactarm 76. If the sensing circuitry of the GFCI receptacle senses a groundfault, the coil assembly 50 is energized to draw plunger 52 into thecoil assembly 50 so that banger 54 moves upwardly. As the banger movesupwardly, the banger front dog 58 strikes the latch member 60 causing itto pivot in a counterclockwise direction C about the joint created bythe top edge 82 and inner surface 84 of finger 80. The movement of thelatch member 60 removes the latching finger 64 from engagement with sideR of the remote end 73 of the movable contact arm 70, and permitscontact arm 70 to return to its pre-stressed condition opening contacts72 and 74, seen in FIG. 3. It should be noted that the description thusfar has been in terms of a single latch member 60 and a single contactarm 70. However, there are preferably two sets of latch members 60 andcontact arms 70: one set for the phase (or hot) conductors (line andload side); and the other set for the neutral conductors (line and loadside). Further, the banger 54 preferably has two sets of banger dogs:one set for the phase conductors (line and load side); and the other setfor the neutral conductors (line and load side).

After tripping, the coil assembly 50 is de-energized so that spring 53returns plunger 52 to its original extended position and banger 54 movesto its original position releasing latch member 60. At this time thelatch member 60 is in a lockout position where latch finger 64 inhibitsmovable contact 72 from engaging fixed contact 74, as seen in FIG. 6. Asnoted, latching finger 64 acts as an active inhibitor that prevents thecontacts from touching. Alternatively, the natural bias of movable arm70 can be used as a passive inhibitor that prevents contacts 72 and 74from touching.

To reset the GFCI receptacle so that contacts 72 and 74 are closed andcontinuity between the input and output conductors is reestablished, thereset button 30 is depressed sufficiently to overcome the bias force ofreturn spring 90 and move the latch member 60 in the direction of arrowA, seen in FIG. 4. While the reset button 30 is being depressed, latchfinger 64 contacts side L of the movable contact arm 70 and continueddepression of the reset button 30 forces the latch member to overcomethe stress force exerted by the arm 70 causing the reset contact 62 onthe arm 70 to close on reset contact 63. Closing the reset contactsactivates the operation of the circuit interrupter by, for examplesimulating a fault, so that plunger 52 moves the banger 54 upwardly sothat the banger dog 58 strikes the latch member 60 pivoting the latchmember in the direction of arrow C while the latch member 60 continuesto move in the direction of arrow A. As a result, the latch finger 64 islifted over side L of the remote end 73 of the movable contact arm 70onto side R of the remote end of the movable contact arm, as seen inFIG. 7. Contact arm 70 returns to its unstressed position openingcontacts 62 and 63, so as to terminate the activation of the circuitinterrupting portion, thereby de-energizing the coil assembly 50.

After the circuit interrupter operation is activated, the coil assembly50 is de-energized so that so that plunger 52 returns to its originalextended position, and banger 54 releases the latch member 60 so thatthe latch finger 64 is in a reset position, seen in FIG. 5. Release ofthe reset button causes the latching member 60 and movable contact arm70 to move in the direction of arrow B until contact 72 electricallyengages contact 74.

Referring again to FIGS. 2 and 3 the trip portion according to thisembodiment the present application includes a trip actuator 26,preferably a button, that is movable between a set position, wherecontacts 72 and 74 are permitted to close or make contact, as seen inFIG. 2, and a trip position where contacts 72 and 74 are caused to open,as seen in FIG. 3. Spring 100 normally biases trip button 26 toward theset position. The trip portion also includes a trip arm 102 that extendsfrom the trip button 26 so that a surface 104 of the trip arm 102 movesinto contact with the movable latching member 60, when the trip buttonis moved toward the trip position. When the trip button 26 is in the setposition, surface 104 of trip arm 102 can be in contact with or closeproximity to the movable latching member 60, as seen in FIG. 2.

In operation, upon depression of the trip button 26, the trip buttonpivots about point T of pivot arm 106 extending from strap 24 so thatthe surface 104 of the trip arm 102 can contact the movable latchingmember 60. As the trip button is moved toward the trip position, triparm 102 also enters the path of movement of the finger 80 associatedwith reset button 30 thus blocking the finger 80 from further movementin the direction of arrow A. By blocking the movement of the finger 80,the trip arm 102 inhibits the activation of the reset operation and,thus, inhibits simultaneous activation of the trip and reset operations.Further depression of the trip button 26 causes the movable latchingmember 60 to pivot about point P (FIG. 3) in the direction of arrow C.Pivotal movement of the latching member 60 causes latching finger 64 tomove out of contact with the movable contact arm 70 so that the arm 70returns to its unstressed condition, and the conductive path is broken.Resetting of the device is achieved as described above.

An alternative embodiment of the trip portion will be described withreference to FIGS. 9 and 10. In this embodiment, the trip portionincludes a trip button 26 that is movable between a set position, wherecontacts 72 and 74 are permitted to close or make contact, as seen inFIG. 9, and a trip position where contacts 72 and 74 are caused to open,as seen in FIG. 10. Spring 110 normally biases trip button 26 toward theset position. The trip portion also includes a trip arm 112 that extendsfrom the trip button 26 so that a distal end 114 of the trip arm is inmovable contact with the movable latching member 60. As noted above, themovable latching member 60 is, in this embodiment, common to the trip,circuit interrupting, reset and reset lockout portions and used to make,break or lockout the electrical connections between the input and outputconductive paths.

In this embodiment, the movable latching member 60 includes a rampedportion 60 a which facilitates opening and closing of electricalcontacts 72 and 74 when the trip button 26 is moved between the set andtrip positions, respectively. To illustrate, when the trip button 26 isin the set position, distal end 114 of trip arm 112 contacts the upperside of the ramped portion 60 a, seen in FIG. 9. When the trip button 26is depressed, the distal end 114 of the trip arm 112 moves along theramp and pivots the latching member 60 about point P in the direction ofarrow C causing latching fingers 64 of the latching member 60 to moveout of contact with the movable contact arm 70 so that the arm 70returns to its unstressed condition, and the conductive path is broken.Resetting of the device is achieved as described above.

Using the reset lockout feature described above permits the resetting ofthe GFCI device or any of the other devices in the family of circuitinterrupting devices only if the circuit interrupting portion isoperational. Thus, testing of the circuit interrupting portion occursduring the reset operation. Further, if the circuit interrupting portionbecomes non-operational after the device is set, the independent tripmechanism can still trip the device. In other words, the circuitinterrupting device according to the present application can be trippedwhether or not the circuit interrupting portion is operating properly.

The circuit interrupting device according to the present application canbe used in electrical systems, shown in the exemplary block diagram ofFIG. 11. The system includes a source of power 120, such as ac power ina home, at least one circuit interrupting device 10 electricallyconnected to the power source, and one or more loads 122 connected tothe circuit interrupting device. As an example of one such system, acpower supplied to single gang junction box in a home may be connected toa GFCI receptacle having the above described independent trip and resetlockout features, is installed in the junction box. Household appliancesthat are then plugged into the receptacle become the load or loads ofthe system.

Circuit Breakers

As noted above, various types of circuit interrupting devices arecontemplated by the present application. The resettable receptacle withfault protection described above is one example. Another example is aresettable circuit breaker with fault protection. Generally, suchcircuit breakers are used as resettable branch circuit protectiondevices, which are capable of opening a conductive path supplyingelectrical power to various loads in a power distribution system (orsub-system) if a fault occurs or if the current rating of the circuitbreaker is exceeded. Such circuit breakers are also capable of beingreset to close the conductive path. The conductive path is typicallydivided between a line side and a load side. Thus, the circuit breakerhas line and load phase (or power) connections. The line side has a linephase connection and the load side has a load phase connection. The linephase connection connects to supplied power and the load phaseconnection connects to one or more loads. The connections are connectionpoints where external conductors can be connected to the circuitbreaker. These connections may be, for example, electrical fasteningdevices, such as binding screws, lugs or binding plates, that secure theexternal conductor to the circuit breaker, as well as conductelectricity.

As noted above, the circuit breakers according to the presentapplication can provide fault protection for various types of faults orcombination of faults. Examples of the various faults contemplatedinclude ground faults, arc fault, immersion detection faults, applianceleakage faults and equipment leakage faults. Although many various typesof fault protection circuit breakers are contemplated, the followingdescriptions are for GFCI circuit breakers and AFCI circuit breakers.

Ground Fault Circuit Interrupter Circuit Breakers

An exemplary embodiment of a GFCI circuit breaker incorporating a resetlockout will now be described. Generally, each GFCI circuit breakeraccording to the present application has a circuit interrupting portion,a reset portion and a reset lockout. The GFCI circuit breaker may alsoinclude a trip portion that operates independently of the circuitinterrupting portion.

The circuit interrupting and reset portions preferably useelectromechanical components to break (open) and make (close) theconductive path between the line and load phase connections. However,electrical components, such as solid state switches and supportingcircuitry, may be used to open and close the conductive path. Similar tothe embodiments described above, the circuit interrupting portion isused to automatically break electrical continuity in the conductive path(i.e., open the conductive path) between the line and load phaseconnections upon the detection of a ground fault. The reset portion isused to disable the reset lockout and to permit the closing of theconductive path. That is, the reset portion permits re-establishingelectrical continuity in the conductive path from the line connection tothe load connection. Operation of the reset and reset lockout portionsis in conjunction with the operation of the circuit interruptingportion, so that the electrically conductive path between the line andload phase connections cannot be reset if the circuit interruptingportion is non-operational and/or if an open neutral condition exists.

Circuit breakers with an independent trip portion can still be tripped,i.e., the conductive path between the line and load phase connectionscan still be opened, even if the circuit interrupting portion becomesnon-operational. Preferably, the trip portion is manually activated anduses mechanical components to open the conductive path. However, thetrip portion may use electrical components, such as solid state switchesand supporting circuitry, and/or electromechanical components, such asrelay switches, to open the conductive path between the line and loadphase connections.

Referring now to FIG. 12, the GFCI circuit breaker 200 has a housing 210configured for installation in conventional circuit breaker panels (notshown). Line and load power (phase) connections 212 and 214, and lineand load neutral connections 216 and 218 are accessible from an exteriorof the housing 210 and are provided for connecting the circuit breakerto external wiring. An actuator 220 extends through an exterior surfaceof the housing 210 and is used to manually set the operating conditionor state of the circuit breaker. A trip actuator 222, which will bedescribed in more detail below, extends through the exterior surface ofthe housing 210. The trip actuator 222 is used, in this exemplaryembodiment, to mechanically trip the GFCI circuit breaker independent ofthe operation of the circuit interrupting portion.

Referring to FIG. 13, a power control assembly 224, which forms aportion of the conductive path, is used to make and break the conductivepath. Generally, the power control assembly 224 operates similar to theoperation of a toggle switch. In the exemplary embodiment shown in FIGS.13-18, the power control assembly 224 includes the actuator 220 which ismovable between ‘on’, ‘off’ and ‘trip’ positions and a pair ofelectrical contacts 226 and 228 that are opened and closed dependingupon the state the circuit breaker is in. Preferably, one of thecontacts is fixed relative to the other. For example, in the embodimentshown in FIG. 13, fixed contact 226 is attached to or monolithicallyformed into the line power connection 212, and the movable contact 228is attached to or monolithically formed into movable contact arm 230.However, the present application also contemplates circuit breakerconfigurations where each contact is movable relative to the other.

The movable contact arm 230 is pivotally connected to the actuator 220such that movement of the actuator is translated to movement of thecontact arm 230, or movement of the contact arm 230 is translated tomovement of the actuator 220. Preferably, the contact arm 230 is movablebetween a closed position where contacts 226 and 228 are closed and theconductive path is completed (FIG. 13), and an open position wherecontacts 226 and 228 are open and the conductive path is broken (FIG.14). When the contacts are closed, the circuit breaker 200 is in an ‘on’state so that electricity can flow from the line connection to the loadconnection and the ground fault protection is armed. When the contactsare open, the circuit breaker 200 can be in either a ‘tripped’ state oran ‘off’ state. In the ‘tripped’ state, current cannot flow from theline connection to the load connection and the reset lockout is enabled.In the ‘off’ state current cannot flow from the line connection to theload connection but the reset lockout is not enabled.

A trip/reset assembly 240 is operatively coupled to the power controlassembly 224 and is used for ground fault protection and resetting ofthe circuit breaker 200. In this embodiment, the trip/reset assemblyoperates as the above-described circuit interrupting portion and thereset portion. When the trip/reset assembly operates to provide faultprotection, the assembly operates as the circuit interrupting portion.When the trip/reset assembly 240 operates to reset the circuit breaker,the assembly operates as the reset portion. The trip/reset assembly alsoprovides the current protection for the circuit breaker 200. That is, ifthe current flowing from the line connection to the load connectionexceeds a predetermined current rating for the circuit breaker (e.g., 15amps), then the trip/reset assembly will respond by causing the powercontrol assembly 224 to open the conductive path, e.g., contacts 226 and228 will open.

The trip/reset assembly 240 according to this exemplary embodimentincludes mechanical linkage 242 to the power control assembly andsensing circuitry included on wiring board 244. The sensing circuitry,examples of which are shown in FIGS. 19-21, is used to sense groundfaults and is similar to the sensing circuitry shown in FIG. 8. However,other known circuits capable of detecting ground faults may also beutilized. The test/reset assembly mechanical linkage 242 includescontrol arm 246, latch arm 248 that is movably coupled to latch armsupport 250, and latch arm controller 252. The control arm 246 isoperatively coupled to the movable contact arm 230 via spring 254, sothat if the actuator 220 is in the ‘on’ position (FIG. 13), the controlarm catch 256 is releasably latched to the latch arm 248 to arm theground fault protection, as seen in FIG. 13. Similarly, when theactuator 220 is in the ‘off’ position (FIG. 17) the control arm catch256 is releasably latched to the latch arm 248, as seen in FIG. 17. Whenthe actuator 220 is in the ‘trip’ position (FIG. 14), the control armcatch 256 disengages from the latch arm 248 and the reset lockout isenabled. It should be noted that in this embodiment, the control armcatch 256 also operates as the reset lockout which will be described inmore detail below.

The latch arm controller 252 includes solenoid 258 and latch arm linkage260 which couples the latch arm 248 to the solenoid piston 262 such thatmovement of the solenoid piston is translated to pivotal movement of thelatch arm 248. The trip/reset assembly 240 also includes a reset enableswitch assembly 270 that is activated by switch activator 264 secured tothe latch arm 248. The reset enable switch assembly is provided toinduce or simulate a ground fault condition on the sensing circuitry sothat the circuit interrupting portion is activated to disable the resetlockout, as will be described in more detail below. As noted, the latcharm 248 is pivotally movable relative to the latch arm support 250. Inaddition, the latch arm is also movable in a direction parallel to thelatch arm support 250 such that upward movement of the latch arm 248causes the switch actuator 264 to move in a manner which activates thereset enable switch assembly 270 which, in turn, activates the circuitinterrupting portion, if operational. If the circuit interruptingportion is not operational, the circuit breaker cannot be reset. Variousswitching arrangements for the reset enable switch assembly 270 areshown in FIGS. 19-21. For example, in FIG. 19, the reset enable switchassembly 270 includes a fixed contact 272, that may be a rigid wirestrip, which induces and/or simulates a ground fault when the fixedcontact 272 and the switch actuator 264 of the latch arm 248 come intocontact. Simulating the ground fault causes the solenoid 258 toenergize. The power for the circuit in FIG. 19 is supplied by the lineside connection.

In FIG. 20, the reset enable switch assembly 270 includes a pair ofmomentary switches 274 and 276. In some circuit breaker designs power tothe sensing circuitry is from the load side, so that when the circuitbreaker trips power to the sensing circuit is turned off. In thisembodiment, switch 276 is a normally closed momentary switch. When inthe closed position, switch 276 powers the sensing circuitry from theload side of the breaker contacts and when activated during a resetoperation, momentarily powers the sensing circuitry from the line sideconnection 212 and then returns to the normally closed position if thecircuit breaker resets. Switch 274 is preferably configured so that itis opened when contacts 226, 228 are closed, and so that it is closedwhen the breaker contacts 226, 228 are opened. To avoid unintendedsimulated ground fault conditions, switch 274 opens before the circuitbreaker contacts 226, 228 close, and switch 274 closes after the circuitbreaker contacts 226, 228 open. This functions to introduce a simulatedfault condition to the sensing circuitry. As the sensing circuitry isbeing powered from the load side and the breaker contacts are open thesolenoid 258 is not activated. When a reset operation is being performedso that power is temporarily switched to the line side by switch 276,the solenoid is capable of being energized to permit resetting of thecircuit breaker.

In FIG. 21, the reset enable switch assembly 270 includes a series ofswitch contacts 280, 282, 284, 286 and 288 which are sequentiallyactivated or deactivated (depending upon their normal state) by pressurefrom the switch actuator 264 as the latch arm 248 moves in direction U(FIG. 15) when moving actuator 220 to the ‘off’ position. For example,initial motion of the switch actuator 264 breaks contact 280 fromcontact 282. Continued pressure causes contact 282 to close with contact284. Further pressure causes contact 286 to close with contact 288 whichintroduces a phase voltage to the sensing circuitry, thus, simulating aground fault. It should be noted that in both embodiments, power isconnected to the sensing circuitry from the load connection side whenthe circuit breaker 200 is in the ‘on’, ‘off’ or ‘tripped’ states, andpower is supplied to the sensing circuitry from the line connection sidewhile resetting the circuit breaker.

To prevent multiple firings of the solenoid, the reset enable switchassembly is preferably configured to induce and/or simulate the groundfault condition while in the lock-out condition until solenoid 258 tripslatch arm 248 and releases control arm catch 256 or actuator 220 isreleased. Thus, in the embodiment of FIG. 19, the switch actuator 264 ispositioned on the latch arm 248 so that when the reset lockout isdisabled, the latch arm 248, and thus the switch actuator 264, move awayfrom the reset enable switch assembly in response to the biasing forceof spring 265, so that the switch becomes deactivated.

The portion of the trip/reset assembly used to perform the trippingoperation is also designated as the circuit interrupting portion, andthe portion of the trip/reset assembly used to perform the resetoperation is also designated as the reset portion. Further, the portionof the trip/reset assembly used to perform current protection is alsodesignated as the current protection portion.

Referring now to FIGS. 14 and 15, the reset lockout inhibits theactuator 220 in the power control assembly 220 from moving from the‘tripped’ position to the ‘off’ position so that the circuit breakercannot be reset. In the embodiment shown in FIGS. 14 and 15, the resetlockout operates as an active lockout in which the lockout activelyinhibits (or prevents) the actuator 220 from moving from the ‘tripped’position to the ‘off’ position. However, the reset lockout may also beconfigured to passively inhibit movement of the actuator 220 by, forexample, the inherent operation of a spring. The reset lockout includesthe control arm catch 256 attached to or formed into the control arm 246so that when the actuator 220 is manually moved in the direction ofarrow F, toward the ‘off’ position, the catch 256 engages surface 248 aof the latch arm 248 which inhibits movement of the actuator 220.

In this embodiment, the conductive path extends from line powerconnection 212 to load power connection 214 via the power controlassembly 224, the trip/reset assembly and transformer assembly 290. Thetransformer assembly includes a differential transformer andground/neutral coil shown in FIGS. 19 and 20.

Typically, circuit breakers are reset by first moving the actuator 220to the ‘off’ position and then moving the actuator to the ‘on’ position.While this sequence of movements of the actuator are being performed,the control arm 246 and latch arm 248 are moved so that the control armcatch 256 is releasably latched to the latch arm 248. The circuitbreaker is in the ‘on’ state so that the conductive path is closed andground fault protection is armed.

The operation of the circuit breaker 200 embodiment according to thepresent application will now be described with reference to FIGS. 13-18.As noted, the actuator 220 is movable between ‘on’, ‘off’ and ‘trip’positions, where the ‘trip’ position is typically between the ‘on’ and‘off’ positions. To put the circuit breaker in the ‘on’ position (fromthe ‘off’ position, FIG. 17) the actuator 220 of the power controlassembly 224 is moved in the direction of arrow O. When in the ‘on’position (FIG. 13), the conductive path between the line and loadconnections is closed, the control arm catch 256 is releasably latchedto the latch arm 248, as seen in FIG. 13, and the reset enable switchassembly 270 is in its normal state. At this point the circuit breakeris in the ‘on’ state, where the ground fault protection is armed and thebreaker is capable of tripping.

If a fault is detected by the sensing circuitry, the solenoid 258 isenergized so that the solenoid piston 262 retracts, causing the latcharm linkage 260 to pull the latch arm 248 away from the control arm 246.Once the latch arm 248 moves far enough away from the control arm 246the control arm catch 256 is released from the latch arm 248. After thecatch 256 is released, the tension in spring 254 causes the control arm246 to pivot in the direction of arrow P′ permitting arm 230 to pivot indirection P causing contacts 226, 228 to open and the actuator 220 toautomatically move to the ‘trip’ position, seen in FIG. 14. At thistime, the circuit breaker is in the ‘tripped’ state.

When the circuit breaker is in the ‘tripped’ state, the reset lockoutportion of the breaker is enabled, as seen in FIG. 14, so that thecircuit breaker cannot be reset, unless the circuit interrupting portionis operational to disable the reset lockout. FIG. 15 shows the controlarm catch 256 (i.e., the reset lockout) in a lockout position wherecatch 256 is engaged with the surface 248 a of the latch arm 248, thuspreventing further movement of the actuator 220 toward the ‘off’position.

To reset the circuit breaker, further movement of the actuator 220 inthe direction of arrow F activates reset enable switch assembly 270 sothat if the circuit interrupting portion is operational, the solenoid258 will energize causing the latch arm linkage 260 and thus the latcharm 248 to retract. When the latch arm 248 retracts, the control armcatch 256 disengages from the latch arm 248 so that the actuator 220 isno longer inhibited from moving to the ‘off’ position, as seen in FIG.17.

Referring again to FIGS. 13 and 14 the trip portion according to thisembodiment of the present application includes the trip actuator 222 anda trip arm 292. Preferably, the trip actuator 222 is a button that ismovable between a set position, where contacts 226 and 228 are permittedto close (seen in FIG. 13) and a trip position where contacts 226 and228 are caused to open (seen in FIG. 14). Spring 294 normally biasestrip button 222 toward the set position. The trip arm 292 that extendsfrom the trip button 222 so that a surface 296 of the trip arm 292 canmove into contact with the control arm 246 when the trip button 222 ismoved toward the trip position (i.e., when the trip button isdepressed).

To trip the circuit breaker 200 independently of the operation of thecircuit interrupting portion, the trip actuator 222 is depressed so thatsurface 296 of trip arm 292 pushes against the control arm 246 andsurface 309 of trip arm 292 pushes against latch arm 248 causing thecontrol arm catch 256 to release from the latch arm 248. The tension inspring 254 causes the contact arm 246 and thus contact 228 to pivot awayfrom the fixed contact 226, thus opening the conductive path.

Arc Fault Circuit Interrupter Circuit Breakers

An exemplary embodiment of an AFCI circuit breaker incorporating a resetlockout will now be described. Generally, each AFCI circuit breakeraccording to the present application has a circuit interrupting portion,a reset portion and a reset lockout. Similar to the GFCI circuitbreaker, the circuit interrupting and reset portions preferably useelectromechanical components to break (open) and make (close) theconductive path between the line and load phase connections. However,electrical components, such as solid state switches and supportingcircuitry, may be used to open and close the conductive path. Similar tothe embodiments described above, the circuit interrupting portion isused to automatically break electrical continuity in the conductive path(i.e., open the conductive path) between the line and load phaseconnections upon the detection of an arc fault. The reset portion isused to disable the reset lockout and to permit the closing of theconductive path. That is, the reset portion permits re-establishingelectrical continuity in the conductive path from the line sideconnection to the load side connection. Operation of the reset and resetlockout portions is in conjunction with the operation of the circuitinterrupting portion so that the electrically conductive path betweenthe line and load phase connections cannot be reset if the circuitinterrupting portion is non-operational and/or if an open neutralcondition exists.

Similar to the GFCI circuit breaker, the AFCI circuit breaker may alsoinclude a trip portion that operates independently of the circuitinterrupting portion. AFCI circuit breakers with this trip portion canstill be tripped, i.e., the conductive path between the line and loadphase connections can still be opened, even if the circuit interruptingportion becomes non-operational. Preferably, the trip portion ismanually activated and uses mechanical components to open the conductivepath. However, the trip portion may use electrical components, such assolid state switches and supporting circuitry, and/or electromechanicalcomponents, such as relay switches and supporting circuitry, to open theconductive path between the line and load phase connections.

The circuit interrupting, reset, reset lockout and optional tripportions according to this embodiment are substantially the same asthose for the above-described GFCI circuit breaker embodiment. Theseportions are shown in FIGS. 12-18 and for simplicity the descriptions ofthese portions are not repeated. A difference between the GFCI and theAFCI circuit breakers is the sensing circuitry used to detect faults.FIGS. 22-24 show one exemplary embodiment of the sensing circuitry thatcan be used to detect arc faults. However, a more detailed descriptionof the arc fault sensing circuitry can be found in commonly owned,co-pending application Ser. No. 08/994,772, filed Dec. 19, 1997 which isincorporated herein in its entirety by reference. In addition,alternative techniques for sensing arc faults are provided in commonlyowned, copending applications Ser. Nos. 08/993,745 and 08/995,130 bothof which are incorporated herein by reference.

Generally, the sensing circuitry can be configured to monitor the phaseconductive path 410 (FIG. 22) at either the line side of the conductivepath, the load side of the conductive path or at both the line and loadsides of the conductive path. The sensing circuitry can also beconfigured to implement many of the various techniques capable ofmonitoring one or more conductive paths and determining whether signalson a conductive path comprise an arc fault. Similar to the abovedescribed GFCI circuit breaker embodiment, the sensing circuitry alsooperates to interrupt the AC power on at least the phase conductive pathby opening contacts 226 and 228 (Seen in FIG. 13) via the actuation ofsolenoid 258.

In the embodiment of FIG. 22, the conductive path 410 extends from linepower connection 212 to load power connection 214 via the power controlassembly 224, the trip/reset assembly 240 and transformer assembly 430.

The following is a description of an exemplary embodiment of the sensingcircuitry contemplated by the present application. Referring to FIG. 22,the sensing circuitry includes a path control portion 411, a pickupportion 412 and a processing portion 414. The path control portion 411provides power to the circuitry used to detect arc faults and to thecomponents used to open the conductive path if an arc fault is detected.The pickup portion 412 monitors the conductive path 410 and picks upspurious signals from the conductive path, which may include arc faults.The processing portion 414 receives the arcing signals and 1) determineswhether the arcing signals include an arc fault, and 2) provides atrigger signal to open the conductive path if an arc fault is detected.

Referring to FIG. 23 an exemplary schematic diagram for the path controland pickup portions 411 and 412 is shown. In this embodiment, the pathcontrol portion 411 includes a power supply circuit 418 connected to theline phase and neutral connections 212 and 216 respectively, and an SCR422 that selectively energizes solenoid 258. The power supply alsoprovides power, typically 26 volts, to the processing circuitry throughvoltage dropping resistor 417 and capacitor 419, shown in FIG. 23.Capacitor 423 prevents voltage spikes on the line from causing the SCR422 to inadvertently trigger, and resistor 425 prevents the gate of theSCR 422 from floating and ensures that the SCR turns off when theTRIG_AFCI signal (described below) goes away. Resistor 427 is used todrop the voltage from the TRIG_AFCI signal to a level suitable for theSCR 422.

The pickup portion 412 includes transformer assembly 430 which picks upspurious signals, which may include arc faults, on the conductive path410. However, the spurious signals can also be detected using capacitivecoupling via capacitors coupled to the conductive path 410. Techniquesof using capacitive coupling onto the AC line to detect spurious voltagesignals are known and can be used instead of the transformer assembly430. The transformer assembly 430 includes a magnetic core 431 and acoil 432 constructed using, for example, known toroidal ferrite designtechniques. Preferably, the ferrite material and the turn ratio of themagnetic core 431 and coil 432 are chosen to achieve a natural resonanceat about 1.5 MHz. A resistor 434 in combination with capacitor 436 forma resonance damping network for broadband frequency pickup. Thisconfiguration enables the sensing circuitry to react to a wider range ofspurious signals from different sources rather than limiting the sensingcircuitry to detecting signals within a limited frequency spectrum.

The signal generated by transformer assembly 430 is transferred tocapacitor 438 which performs a DC decoupling function, and diodes 440,442 prevent low level signals below about 0.6 V peak to peak fromentering the processing circuitry. The signal output by the pickupportion 412 is identified as an arcing signal, labeled ARC_SENSE, and istransferred to the processing portion 414. As noted, the processingportion determines whether the spurious signal, ARC_SENSE, includescharacteristics that qualify as an arc fault.

A schematic diagram illustrating the processing circuitry 414 is shownin FIG. 24. The processing circuit 414 includes an amplifier 450, afilter 452, a rectifier 454, and a peak detector 456.

The amplifier 450 includes a resistor divider network that includesresistors 458 and 460 which determine the maximum dynamic range of theamplifier 450. The amplifier 450 also includes an operational amplifier(op amp) 462 having a fixed gain provided by resistors 464 and 466. Theplus input of the op amp 462 is tied to ground potential by resistor468, and the minus input to the op amp 462 is connected to the junctionof resistors 464 and 466, as shown in FIG. 24.

The output of the op amp 462 is input to frequency selective circuitry,such as filter 452. Preferably, the filter 452 is a 2^(nd) orderButterworth high pass active filter, which provides better cut offresponse than passive filters. However, passive type filter designs,such as LC filters, can also be used. The filter 452 includes an op amp470 connected to an RC network including capacitors 472, 474 andresistors 476, 478, 480, which perform the filtering function. Utilizingcapacitors and resistors in conjunction with the op amp 470 provides asteeper roll off in frequency gain below 500 KHz than would be achievedwith passive components alone. Preferably, the internal operatingcharacteristics of the op amp 470 provide the upper limit to the highfrequencies passed by the filter 452. To permit maximum utilization ofthe high frequency characteristics of the op amp 470, the gain of the opamp is preferably set at unity. Filter 452 permits the detection of arcfaults even if the AC power lines (including the conductive path) arebeing used for data communications which typically occur at frequenciesbelow 500 KHz.

The output of the filter 452 is input to the rectifier 454 which ispreferably a full wave rectifier. The rectifier 454 includes an op amp482 having its plus input connected to ground and its minus inputconnected to its feedback path. The rectifier 454 provides a variablelevel of gain, depending on whether the input signal from the filter 452is positive or negative. To illustrate, for positive input signals thegain is zero and for negative signals the gain is determined by theratio of resistors 484 and 486. If the input signal is positive relativeto ground, the output of the op amp 482 is negative which pulls theminus input of the op amp down through diode 488 until it is equal tothe plus input. Thus, the amplifier has a gain of zero. If, on the otherhand, the signal input to the minus input is negative relative toground, the output of the op amp 482 is positive and feedback currentflows through diode 490 and resistor 486.

The signal output from the rectifier 454 is in the form of a pulsed DCvoltage, which is fed to the peak detector 456. The peak detector 456has a constant current source that includes op amp 492, diode 494 andresistors 496, 498 and 499. The constant current source is responsive tothe pulsed DC voltage from the rectifier 454, and provides a linearcharging curve across capacitor 500. The rate of charging of thecapacitor 500 is proportional to the number of positive signals input tothe peak detector from the rectifier 454.

As shown in FIG. 24, capacitor 500 is continually being dischargedthrough resistor 502. In addition, the peak detector 456 functions as anintegrator and a time delay circuit which aids in preventing the circuitfrom reacting to acceptable short lived arcing spikes created when, forexample, a switch is thrown or an appliance is plugged in.

The arcing signals being detected by the processing circuitry 414 can becategorized into three main types: high, low and very low arcingsignals. In the presence of a high arcing signal, the output of therectifier 454 includes a substantial number of DC pulses so that thecurrent output by the constant current source rapidly charges thecapacitor 500 causing the voltage across the capacitor to reach a zenerdiode breakdown voltage of output transistor 504 relatively quickly.

When the signal detected is a low arcing signal, the peak detector 456generates pulses that are more dispersed, causing the voltage acrosscapacitor 500 to rise more slowly, thus delaying the breakover of thezener diode breakdown voltage of transistor 504. In this instance,although resistor 502 continuously discharges the capacitor 500, if thepulses from the rectifier 454 continue for a sufficient enough time tocompletely charge the capacitor 500, breakover of the zener diodebreakdown voltage of transistor 504 can occur.

When the signal detected is a very low arcing signal, the discharge rateof the capacitor 500 via resistor 502 is greater than or equal to thecharging rate of the capacitor 500. Thus, the voltage across thecapacitor 500 does not reach a sufficiently high level to causebreakover of the zener diode breakdown voltage of transistor 504.

The output of transistor 504, labeled TRIG_AFCI, is the trigger signalfor the SCR 422 (seen in FIG. 23). Thus, the TRIG_AFCI signal is inputto the gate of the SCR 422 through resistor 427 which turns on the SCRand thus energizes the solenoid 258. As described above, energization ofthe solenoid 258 causes the contacts 226 and 228 to open or permitsresetting of the circuit breaker. The solenoid 258 is de-energized afterthe gate signal is removed and the rectified AC decreases to a levelclose to zero. As noted, resistor 425 ensures that the gate of the SCR422 turns off when there is no TRIG_AFCI signal. It should be noted thatif an arc is upstream from the circuit breaker, opening the contactsstops the pickup portion from picking up spurious signals (including thearc). If the arc is downstream from the circuit breaker, opening thecontacts extinguishes the arc and, thus, removes the TRIG_AFCI signal.

The operation of the AFCI circuit breaker is similar to the operation ofthe GFCI circuit breaker described above with reference to FIGS. 13-18.In operation, the actuator 220 is movable between ‘on’, ‘off’ and ‘trip’positions, where the ‘trip’ position is typically between the ‘on’ and‘off’ positions. To put the circuit breaker in the ‘on’ position (fromthe ‘off’ position, FIG. 17) the actuator 220 of the power controlassembly 224 is moved in the direction of arrow O. When in the ‘on’position (FIG. 13), the conductive path between the line and loadconnections is closed, the control arm catch 256 is releasably latchedto the latch arm 248, as seen in FIG. 13, and the reset enable switchassembly 270 is in its normal state. At this point the circuit breakeris in the ‘on’ state, where the arc fault protection is armed and thebreaker is capable of tripping.

If an arc fault is detected by the sensing circuitry described above forFIGS. 22-24, the solenoid 258 is energized so that the solenoid piston262 retracts, causing the latch arm linkage 260 to pull the latch arm248 away from the control arm 246. Once the latch arm 248 moves farenough away from the control arm 246 the control arm catch 256 isreleased from the latch arm 248. After the catch 256 is released, thetension in spring 254 causes the control arm 246 to pivot in thedirection of arrow P permitting arm 230 to pivot in a direction P′causing contacts 226, 228 to open and the actuator 220 to automaticallymove to the ‘trip’ position, seen in FIG. 14. At this time, the circuitbreaker is in the ‘tripped’ state.

When the circuit breaker is in the ‘tripped’ state, the reset lockoutportion of the breaker is enabled, as seen in FIG. 14, so that thecircuit breaker cannot be reset, unless the circuit interrupting portionis operational to disable the reset lockout. FIG. 15 shows the controlarm catch 256 (i.e., the reset lockout) in a lockout position wherecatch 256 is engaged with the surface 248 a of the latch arm 248, thuspreventing further movement of the actuator 220 toward the ‘off’position.

To reset the circuit breaker, further movement of the actuator 220 inthe direction of arrow F activates reset enable switch assembly 270 byclosing switch 271, which is preferably a momentary switch. Closingswitch 271 triggers pulse generator 273 which outputs a pulse that turnson oscillator 275 for a finite period of time at a resonant frequency ofabout 1.5 MHz. An example of a suitable pulse is a 10 ms pulse at lowcurrent, e.g., in the order of about 1-10 mA. If the circuitinterrupting portion is operational, activation of the reset enableswitch assembly 270, which simulates a fault, energizes the solenoid 258causing the latch arm linkage 260 and thus the latch arm 248 to retract.When the latch arm 248 retracts, the control arm catch 256 disengagesfrom the latch arm 248 so that the actuator 220 is no longer inhibitedfrom moving to the ‘off’ position, as seen in FIG. 17.

Circuit Breakers With Combined Fault Detection Capabilities

The present application also contemplates circuit breakers thatincorporate fault protection capabilities for more than one type offault. For example, the circuit breaker can be configured with groundfault and arc fault protection, or the circuit breaker can be configuredwith ground fault and immersion detection fault protection. Theconstruction of such circuit breakers can be similar to that shown inFIGS. 12-18 and for simplicity is not repeated. That is, such circuitbreakers would include a circuit interrupting portion, a reset portion,a reset lockout portion and, optionally, an independent trip portion. Adifference in such combined fault protection circuit breakers would bein the sensing circuitry used to detect faults. The block diagram ofFIG. 22 in combination with the schematic diagram of FIG. 25 show thesensing circuitry for one embodiment for a circuit breaker having groundfault and arc fault protection capabilities. FIGS. 26-30 show sensingcircuitry for another embodiment for a circuit breaker having groundfault and arc fault protection capabilities. These embodiments areexemplary. The present application contemplates circuit breakers withany number of fault protection capabilities in any combination.

The following description of FIG. 25 is an exemplary embodiment ofsensing circuitry suitable for use in a circuit breaker with combinedfault protection capabilities. In this embodiment, the conductive path410 extends from line power connection 212 to load power connection 214via the power control assembly 224 (seen in FIG. 13), the trip/resetassembly 240 (seen in FIG. 13), transformer assembly 550 and transformerassembly 552. Generally, the sensing circuitry includes a path controlportion 411, a pickup portion 412 and a processing portion 414 (seen inFIG. 24) similar to the embodiment of FIG. 22. The path control portion411 provides power to the circuitry used to detect ground faults and arcfaults, and to the components used to open the conductive path if aground fault or an arc fault is detected. The pickup portion 412monitors the conductive path 410 and picks up 1) ground faults andgrounded neutral faults, and 2) spurious signals from the conductivepath which may include arc faults. The processing portion 414 (seen inFIG. 24) receives arcing signals from the pick up portion and 1)determines whether the spurious signals include an arc fault, and 2)provides a trigger signal to open the conductive path if an arc fault isdetected. In this embodiment, the processing portion 414 is the same asthe processing portion 414 described above with reference to FIG. 24 andis not repeated.

Referring again to FIG. 25, the path control portion 411 includes apower supply circuit 560 connected to the line phase and neutralconnections 212 and 216 respectively, SCR 562 and SCR trigger circuit564. The power supply provides power, typically rectified AC, to the SCR562, and provides power, typically 26 volts, to the components in thepickup and processing portions 412 and 414, and to the GFCI portion. Thesolenoid 258 is selectively energized in response to the output of SCRtrigger circuit 564, which results in the opening and/or closing ofcontacts 226 and 228. Preferably, the SCR trigger circuit 564 performsan OR function so that either a ground fault or an arc fault triggersignal triggers the SCR 562.

The pickup portion 412 includes a ground fault pickup and an arc faultpickup. The ground fault pick up includes transformer assembly 550having a differential transformer 570 and a ground neutral transformer572 both coupled to an integrated circuit 580. The integrated circuit580 is used to detect ground faults and to output a trigger signal,labeled TRIG_GFCI, to the SCR trigger circuit 564. Examples of suitableintegrated circuits include the National Semiconductor LM1851 and theRaytheon RA9031. As noted above, such ground fault sensing circuitry isknown.

The arc fault pickup includes transformer assembly 552 which picks upspurious current signals, which may include arc faults, on theconductive path. However, spurious voltage signals can also be detectedusing capacitive coupling via capacitors coupled to the phase conductivepath. Techniques of using capacitive coupling onto the AC line areknown.

The transformer assembly 552 has a magnetic core 590 and a coil 592constructed using, for example, known toroidal ferrite designtechniques. Preferably, the ferrite material and the turn ratio of themagnetic core 590 and coil 592 are chosen to achieve a natural resonanceat about 1.5 MHz. A resistor 594 in combination with capacitor 596 formsa resonance damping network for broadband frequency pickup. Thisconfiguration of the arc fault pickup enables the sensing circuitry toreact to a wider range of spurious signals from different sources ratherthan limiting the sensing circuitry to detecting signals within alimited frequency spectrum.

The signal generated by transformer assembly 552 is transferred tocapacitor 598 which performs a DC decoupling function, and diodes 600,602 prevent low level signals below about 0.6 V peak to peak fromentering the processing circuitry 414. The signal output by the pickupportion is identified as an arcing signal, labeled ARC_SENSE, and istransferred to the processing portion 414. As noted, the processingportion determines whether the spurious signal includes characteristicsthat qualify it as an arc fault.

The operation of the circuit breaker with combined fault protectioncapabilities according to the embodiment of FIGS. 22 and 25 is similarto the operation of the GFCI and AFCI circuit breakers described abovewith reference to FIGS. 13-24, except that it is responsive to thedetection of one or more types of faults.

In operation, the actuator 220 (seen in FIG. 17) is movable between‘on’, ‘off’ and ‘trip’ positions, where the ‘trip’ position is typicallybetween the ‘on’ and ‘off’ positions. To put the circuit breaker in the‘on’ position (from the ‘off’ position, FIG. 17) the actuator 220 of thepower control assembly 224 is moved in the direction of arrow O. When inthe ‘on’ position (FIG. 13), the conductive path between the line andload connections is closed, the control arm catch 256 is releasablylatched to the latch arm 248, as seen in FIG. 13, and the reset enableswitch assembly 270 is in its normal state. At this point the circuitbreaker is in the ‘on’ state, where fault protection is armed and thebreaker is capable of tripping.

If a fault (e.g., an arc fault or a ground fault) is detected by thesensing circuitry described above for FIGS. 22 and 25, the solenoid 258is energized so that the solenoid piston 262 retracts, causing the latcharm linkage 260 to pull the latch arm 248 away from the control arm 246.Once the latch arm 248 moves far enough away from the control arm 246the control arm catch 256 is released from the latch arm 248. After thecatch 256 is released, the tension in spring 254 causes the control arm246 to pivot in the direction of arrow P′ permitting arm 230 to pivot ina direction P causing contacts 226, 228 to open and the actuator 220 toautomatically move to the ‘trip’ position, seen in FIG. 14. At thistime, the circuit breaker is in the ‘tripped’ state.

When the circuit breaker is in the ‘tripped’ state, the reset lockoutportion of the breaker is enabled, as seen in FIG. 14, so that thecircuit breaker cannot be reset, unless the circuit interrupting portionis operational to disable the reset lockout. FIG. 15 shows the controlarm catch 256 (i.e., the reset lockout) in a lockout position wherecatch 256 is engaged with the surface 248 a of the latch arm 248, thuspreventing further movement of the actuator 220 toward the ‘off’position.

To reset the circuit breaker, further movement of the actuator 220 (seenin FIG. 16) in the direction of arrow F activates reset enable switchassembly 270 (seen in FIG. 25) by closing switch 271, which ispreferably a momentary switch. Closing switch 271 triggers pulsegenerator 273 which outputs a pulse that turns on oscillator 275 for afinite period of time at a resonant frequency of about 1.5 MHz. Anexample of a suitable pulse is a 10 ms pulse at a low current, e.g., inthe order of about 1-10 mA. If the circuit interrupting portion isoperational, activation of the reset enable switch assembly 270, whichsimulates a fault, energizes the solenoid 258 causing the latch armlinkage 260 and thus the latch arm 248 to retract. When the latch arm248 retracts, the control arm catch 256 disengages from the latch arm248 so that the actuator 220 is no longer inhibited from moving to the‘off’ position, as seen in FIG. 17.

It should be noted that in the embodiment of FIG. 25, the GFCI portionis not activated for reset. However, it may be desirable to activatetest circuits for both the GFCI and AFCI portions of the device, so thatwhen resetting the device, both portions are tested before the device isreset. A description of this embodiment is described within theembodiment below.

It may be desirable for the sensing circuitry to generally pinpoint thelocation of an arc fault within a branch circuit. To accomplish this, asecond arc fault pickup is added to the pickup portion 412, shown inFIG. 25, so that the pickup portion 412 outputs two separate arcingsignals representing arcing signals picked up on the line and loadsides. This embodiment of the sensing circuitry is shown in FIGS. 26-30.

In this embodiment, the AC line (i.e., the line phase and neutralconductive paths) is partitioned into two different segments separatedby the ground fault pickup of the pickup portion 412. The AC line issplit for high frequency signals while the normal 50 or 60 Hz powertransmission is unaffected. Referring to FIG. 27, the line and load arcfault pickups are, preferably, separated by the transformer assemblies570 and 572 and ferrite transformers or beads 604 and 606 located oneach side of the transformer assemblies. The ferrite transformersfunction to enhance the impedance of the AC line to high frequencysignals.

The line side arc fault pickup includes transformer assembly 610 havinga magnetic core 612 and a coil 614. The magnetic core 612 and coil 614are constructed using, for example, known toroidal ferrite designtechniques. Preferably, the ferrite material and the turn ratio of themagnetic core 612 and coil 614 are chosen to achieve a natural resonanceat about 1.5 MHz. A resistor 616 in combination with capacitor 618 forma resonance damping network for broadband frequency pickup. Thisconfiguration enables the sensing circuitry to react to a wider range ofspurious signals from different sources rather than limiting the sensingcircuitry to detecting signals within a limited frequency spectrum. Theload side pickup is the same as the arc fault pickup described abovewith reference to FIG. 25 and for simplicity is not repeated.

Similar to the above-described embodiments, the arcing signal can alsobe detected using capacitive coupling via capacitors on both the lineside pickup and the load side pickup. Techniques of using capacitivecoupling onto the AC line are known.

Schematic diagrams illustrating the line processing circuitry 414 a andthe load processing circuitry 414 b are shown in FIGS. 28 and 29,respectively. In this embodiment each processing circuit includes fourprocessing stages; an AGC amplifier, a filter, a rectifier and a peakdetector.

Referring to FIG. 28, in the line processing circuitry 414 a, theLINE_ARC_SENSE signal is fed into the AGC amplifier 620, which includesa first resistor divider network having resistors 630, 632 and 634 thatdetermine the maximum dynamic range of the AGC amplifier 620. Feedbackcontrol is provided through field effect transistor (FET) 636, whichacts as a variable resistance in parallel with resistor 632. A secondresistor divider network that includes resistors 638 and 640 provides avoltage level for the gate of FET 636. Preferably, a feedback signal,labeled LINE_AGC, input to FET 636 is proportional to a signal leveldeveloped on the load side. Similarly, a feedback signal, labeledLOAD_AGC, fed back to the AGC amplifier in the load circuitry (describedhereinbelow in connection with FIG. 29) is preferably proportional tothe signal level developed on the line side. This configuration providesadditional differentiation between the line side and load side arcingsignals sensed by the arc fault pickup.

The AGC amplifier 620 also includes an operational amplifier (op amp)642 having a fixed gain provided by resistors 644 and 646. Resistor 644is preferably a variable resistor that permits matching of the base gainof the AGC amplifier in both the line processing circuitry 414 a and theload processing circuitry 414 b. The plus input of the op amp 642 isconnected to ground by resistor 648, and the minus input of the op ampis connected to resistors 644 and 646 as shown. To illustrate the effectof the feedback of the FET 636, assume that resistors 630, 632 and 634are equal. With no feedback on the LINE_AGC signal, FET 636 is an opencircuit and 67% of the LINE_ARC_SENSE signal enters op-amp 642. Withfull feedback on the LINE_AGC, the FET 636 is saturated so that only 50%of the LINE_ARC_SENSE signal enters the op-amp 642. By altering thevalues of resistors 630, 632 and 634 and resistors 638 and 640, theweight and responsiveness of the AGC amplifier can be varied.

The output of the op amp 642 is input to frequency selective circuitry,such as filter 622. Preferably, the filter 622 is a 2^(nd) orderButterworth high pass active filter, which provides better cut offresponse than passive filters. However, passive type filter designs,such as LC filters, can also be used.

Preferably, the filter 622 includes an op amp 650 connected to an RCnetwork including capacitors 652, 654 and resistors 656, 658, 660 whichperform the filtering function. Utilizing capacitors and resistors inconjunction with the op amp 650 provides a steeper roll off in frequencygain below 500 KHz than would typically be achieved with passivecomponents alone. Preferably, the internal operating characteristics ofthe op amp 650 provide the upper limit to the high frequencies passed bythe filter 622. To permit maximum utilization of the high frequencycharacteristics of the op amp 650, the gain of the op amp is preferablyset at unity. Filter 622 permits the detection of arc faults even if theAC power lines (including the conductive path) are being used for datacommunications which typically occur at frequencies below 500 KHz.

The output of the filter 622 is input to the rectifier 624, which ispreferably a full wave rectifier. Preferably, the rectifier 624 isconfigured to rectify input voltages in the millivolt range, and toprovide a DC voltage for the peak detectors 626. The rectifier 624includes an op amp 670 having its plus input connected to ground and itsminus input connected to its feedback path. The rectifier 624 provides avariable level of gain, depending on whether the input signal from thefilter 622 is positive or negative. To illustrate, for positive inputsignals the gain is zero, and for negative signals the gain ispreferably determined by the ratio of resistors 672 and 674. If theinput signal is positive relative to ground, the output of the op amp670 is negative which pulls the minus input of the op amp down throughdiode 676 until it is equal to the plus input. Thus, the op amp 670 hasa gain of zero. If, on the other hand, the signal input to the minusinput is negative relative to ground, the output of the op amp 674 ispositive and feedback current flows through diode 678 and resistor 674and the gain is set by resistors 672 and 674.

The signal output from the rectifier 624 is in the form of a pulsed DCvoltage, which is fed to the peak detector 626. The peak detector 626has a constant current source that includes op amp 680, diode 682 andresistors 684, 686 and 688. The constant current source is responsive tothe pulsed DC voltage from the rectifier 624 and provides a linearcharging curve across capacitor 690. The rate of charging of thecapacitor 690 is proportional to the number of positive signals input tothe peak detector 626 from the rectifier 624.

As shown in FIG. 28, capacitor 690 is continually being dischargedthrough resistor 692. In addition, the peak detector 626 functions as anintegrator and a time delay circuit which aids in preventing the circuitfrom reacting to acceptable short lived arcing spikes created when, forexample, a switch is thrown or an appliance is plugged in.

The arcing signals being detected by the processing circuitry 414 a canbe categorized into three main types: high, low and very low arcingsignals. In the presence of a high arcing signal, the output of therectifier 624 includes a substantial number of DC pulses so that thecurrent output by the constant current source rapidly charges thecapacitor 690 causing the voltage across the capacitor 690 to reach azener diode breakdown voltage of output transistor 694 relativelyquickly.

When the signal detected is a low arcing signal, the peak detector 626generates pulses that are more dispersed, causing the voltage acrosscapacitor 690 to rise more slowly, thus delaying the breakover of thezener diode breakdown voltage of transistor 694. In this instance,although resistor 692 continuously discharges the capacitor 690, if thepulses from the rectifier 624 continue for a sufficient enough time tocompletely charge the capacitor 690, breakover of the zener diodebreakdown voltage of transistor 694 can occur.

When the signal detected is a very low arcing signal, the discharge rateof the capacitor 690 via resistor 692 is greater than or equal to thecharging rate of the capacitor 690. Thus, the voltage across thecapacitor 690 does not reach a sufficiently high level to causebreakover of the zener diode breakdown voltage of transistor 694.

The output of transistor 694, labeled LINE_OUT, is input to arc faulttrigger generator 700 (seen in FIG. 30), which as described belowprovides the trigger signal for the SCR 562 causing the solenoid 258 tobe energized and contacts 226 and 228 to open or permits resetting ofthe circuit breaker. Further, the output voltage of peak detector 626,designated LOAD_AGC, is used as the feedback signal for the AGCamplifier in the load processing circuitry 414 b.

Referring now to FIG. 29 the load processing circuitry 414 b is shown.In the load processing circuitry, the LOAD_ARC_SENSE signal is fed intoan AGC amplifier 710 having a first resistor divider network thatincludes resistors 712, 714 and 716, and determines the maximum dynamicrange of the AGC amplifier 710. Feedback control is provided throughfield effect transistor (FET) 718, which acts as a variable resistancein parallel with resistor 714. A second resistor divider network thatincludes resistors 720 and 722 provides a voltage level for the gate ofFET 718. As noted, preferably, a feedback signal, labeled LOAD_AGC,input to FET 718 is preferably proportional to the LINE_AGC feedbacksignal level developed on the load side.

The AGC amplifier 710 also includes op amp 724 having a fixed gainprovided by resistors 726 and 728. The plus input of the op amp 724 isconnected to ground via resistor 730, and the minus input of the op amp724 is connected to resistors 726 and 728 as shown.

The output of the op amp 724 is input to frequency selective circuitry,such as filter 732. Similar to the line processing circuitry the filter732 is preferably a 2^(nd) order Butterworth high pass active filter,which provides better cut off response than passive filters. However,passive type filter designs, such as LC filters, can also be used.

Preferably, the filter 732 includes an op amp 734 connected to an RCnetwork including capacitors 736, 738 and resistors 740, 742, 744 whichperform the filtering function. Utilizing capacitors and resistors inconjunction with the op amp 734 provides a steeper roll off in frequencygain below 500 KHz than would be achieved with passive components alone.Preferably, the internal operating characteristics of the op amp 734provide the upper limit to the high frequencies passed by the filter732. To permit maximum utilization of the high frequency characteristicsof the op amp 734, the gain of the op amp is preferably set at unity.Filter 732 permits the detection of arc faults even if the AC powerlines (including the conductive path) are being used for datacommunications which typically occur at frequencies below 500 KHz.

The output of the filter 732 is input to the rectifier 750, which ispreferably a full wave rectifier. Preferably, the rectifier 750 isconfigured to rectify input voltages in the millivolt range, andprovides a DC voltage for the peak detector 762. The rectifier 750includes an op amp 752 having its plus input connected to ground and itsminus input connected to its feedback path. The rectifier portionprovides a variable level of gain, depending on whether the input signalfrom the filter portion is positive or negative. To illustrate, forpositive input signals the gain is zero, and for negative signals, thegain is determined by the ratio of resistors 754 and 756. If the inputsignal is positive relative to ground, the output of the op amp 752 isnegative which pulls the minus input of the op amp down through diode760 until it is equal to the plus input. Thus, the amplifier has a gainof zero. If, on the other hand, the signal input to the minus input isnegative relative to ground, the output of the op amp 752 is positiveand feedback current flows through diode 758 and resistor 756 and thegain is set by resistors 754 and 756.

The signal output from the rectifier 750 is in the form of a pulsed DCvoltage, which is fed to the peak detector 762. The peak detector 762has a constant current source that includes op amp 764, diode 766 andresistors 768, 770 and 772. The constant current source is responsive tothe pulsed DC voltage from the rectifier 750, the output of whichprovides a linear charging curve across capacitor 774. Similar to theline processing circuitry 414 a, the rate of charging of capacitor 774is proportional to the number of positive signals input to the peakdetector portion from the rectifier 750.

As seen in FIG. 29, capacitor 774 is continually being dischargedthrough resistor 776. In addition, the peak detector 762 functions as anintegrator and a time delay circuit which aids in preventing the circuitfrom reacting to acceptable short lived arcing spikes created when, forexample, a switch is thrown or an appliance is plugged in.

The arcing signals being detected by the processing circuitry 414 b canbe categorized into three main types: high, low and very low arcingsignals. In the presence of a high arcing signal, the output of therectifier 750 includes a substantial number of DC pulses so that thecurrent output by the constant current source rapidly charges thecapacitor 774 causing the voltage across the capacitor to reach a zenerdiode breakdown voltage of output transistor 778 relatively quickly.

When the signal detected is a low arcing signal, the peak detector 762generates pulses that are more dispersed, causing the voltage acrosscapacitor 774 to rise more slowly, thus delaying the breakover of thezener diode breakdown voltage of transistor 778. In this instance,although resistor 776 continuously discharges the capacitor 774, if thepulses from the rectifier 750 continue for a sufficient enough time tocompletely charge the capacitor 774, breakover of the zener diodebreakdown voltage of transistor 778 can occur.

When the signal detected is a very low arcing signal, the discharge rateof the capacitor 774 via resistor 776 is greater than or equal to thecharging rate of the capacitor 774. Thus, the voltage across thecapacitor 774 does not reach a sufficiently high level to causebreakover of the zener diode breakdown voltage of transistor 778.

The output of transistor 778, labeled LOAD_OUT, is input to the arcfault trigger generator 700, which as described above, will trigger theSCR 562 causing the solenoid 258 to be energized and contacts 226 and228 to open or permits resetting of the circuit breaker.

As noted, the output voltage of peak detector 762, designated LINE_AGC,is used as the feedback signal for the AGC amplifier 620 in the lineprocessing circuitry 414 a.

Referring to FIG. 30, the arc fault trigger generator 700 of the presentapplication will now be described. Once the output signals from the lineprocessing circuitry (LINE_OUT) and the load processing circuitry(LOAD_OUT) exceed their relative zener diode breakdown voltages, theyare fed simultaneously into comparators 780 and 782. The two comparatorcircuits are similar in construction and like components will bedesignated with the same reference numerals.

Resistors 784 and 786 provide input resistance to the respectivecomparator 780 or 782, while resistor 788 provides feedback andresistors 790 and 792 provide adjustable hysteresis for each respectivecomparator. The output of each comparator 780 and 782 is rectified by adiode 794. In one configuration shown in FIG. 30, the rectified outputof each comparator can be converted to a logic “1” or “0” by resistors798 and 800 and zener diodes 802 and 804 and input to an OR function796. The output of the OR function 796 would be the arc fault triggersignal, labeled TRIG_AFCI, input to the SCR trigger circuit 564. Inaddition, the rectified output of comparator 780 can be used to provide,for example, a visual or audible indication via latch 806 and indicator808 that a sensed arc fault occurred on the line side.

In another configuration, the rectified output of comparator 780 can beused to provide, for example, a visual or audible indication viaindicator 808 that a sensed arc fault occurred on the line side. While,the rectified output of comparator 782 can be used as the arc faulttrigger signal to trip or reset the circuit breaker. In this alternativeconfiguration, arc faults sensed on the line side would neither trip thecircuit breaker nor permit resetting of the circuit breaker, but arcfaults sensed on the load side would.

It should be noted that the LINE_OUT and LOAD_OUT signals are input toboth comparators 780 and 782. The LINE_OUT signal is input to the plusinput of comparator 780 and the minus input of comparator 782. TheLOAD_OUT signal is input to the plus input of comparator 782 and theminus input of comparator 780. In this exemplary configuration, thecomparators are prebiased to initially set the outputs of thecomparators 780 and 782 low. Thus, if the LINE_OUT signal is greaterthan the LOAD OUT signal, the output of comparator 780 goes high,assuming the LINE_OUT signal is greater than the breakover voltage oftransistor 694, seen in FIG. 28. If the LOAD_OUT signal is greater thanthe LINE_OUT signal, the output of comparator 782 goes high, assumingthe LOAD_OUT signal is greater than the breakover voltage of transistor778, seen in FIG. 29.

Therefore, if arcing occurs on the load side of the AFCI/GFCI, thesignal generated at the load side pickup will be greater than the signalgenerated at the line side pickup due to the attenuation of highfrequencies caused by the separating impedance. On the other hand,arcing occurring on the line side will generate a larger signal at theline side pickup than at the load side pickup.

In the embodiments described above, both the AFCI and GFCI faultprotection capabilities operate to interrupt the AC power by openingcontacts 226 and 228 via the actuation of solenoid 258. The solenoid 258is actuated by triggering the SCR 562 via the SCR trigger circuit 564.As described above, in one embodiment, the SCR trigger circuit 564 canfunction to provide an OR function to trigger the SCR 562 using knownthyristor triggering techniques when either of its two input triggersignals TRIG_GFCI and TRIG_AFCI go active.

When resetting the circuit breaker, the reset operation can beconfigured so that reset of the circuit breaker can be achieved when oneof the two trigger signals, TRIG_GFCI or TRIG_AFCI, go active. In thisinstance, the SCR trigger circuit 564 would continue to provide the ORfunction.

However, if the SCR trigger circuit 564 is configured as an OR function,then one of the fault protection operations of the circuit breaker needbe operational in order to reset the circuit breaker. To verify thateach fault protection operation of the circuit breaker is operationalwhen the circuit breaker is reset, a test operation for each type offault protection should be provided.

FIG. 31 provides a schematic diagram for an SCR triggering circuit 564that requires each triggering signal to activate before the SCR 562 istriggered and solenoid 258 is energized when resetting the circuitbreaker. In this embodiment, the triggering signals, TRIG_GFCI andTRIG_AFCI, are input to AND gates 820, 822 and 824, as shown, and theoutput of each AND function is input to an OR gate 826. In addition, areset enable signal, labeled RESET_ENA, generated by an additionalswitch in the reset enable switch assembly 270, is also input to the ANDgates 820 and 822, as shown. The output of the OR gate 826 is used asthe trigger signal for the gate of the SCR 562. In this exemplaryconfiguration, when the circuit breaker is in the ‘on’ state and thefault protection is armed, the detection of either a ground fault or anarc fault will trigger the SCR 562 via AND gate 822 or 824 and OR gate826. However, when resetting the circuit breaker, the RESET_ENA signaldisables AND gates 822 and 824, and enables AND gates 820. Thus, onlythe detection of both a ground fault and an arc fault will trigger theSCR 562 via AND gate 820 and OR gate 826 when resetting the circuitbreaker.

Similar to the reset operation for the above described embodiments, thecircuit breaker is reset by moving the actuator 220 in the direction ofarrow F (seen in FIG. 16) to activate reset enable switch assembly 270(seen in FIG. 31) by closing switches 271 a, 271 b and 271 c, which arepreferably momentary switches. Closing switch 271 a clocks latch 830which enables AND gate 820 and disables AND gates 822 and 824. Closingswitch 271 b triggers pulse generator 273 which outputs a pulse thatturns on oscillator 275 for a finite period of time at a resonantfrequency of about 1.5 MHz. An example of a suitable pulse is a 10 mspulse at low current, in the order of about 1-10 mA. It should be notedthat the number of turns on the coil 592 on the transformer assembly 552can be used to control the current from the transformer assembly. If thearc fault circuit interrupting portion is operational, activation ofswitch 271 b simulates an arc fault so that the arc fault triggersignal, TRIG_AFCI, is active. Closing switch 271 c simulates a groundfault so that the ground fault trigger signal, TRIG_GFCI, is active.When TRIG_GFCI goes active, SCR 832 turns on thereby turning ontransistor 834 so that a logic 1 is seen by AND gate 820.

In this configuration, when the latch 830 is clocked and the TRIG_AFCIand TRIG_GFCI lines are active, AND gate 820 outputs a logic 1 whichtriggers the SCR 562 to energize solenoid 258.

The output of AND gate 820 is also connected to the reset input of thelatch 830 via inverter 836. As a result, when AND gate 820 outputs alogic 1, latch 830 is reset, so that gate 820 is disabled and gates 822and 824 are enabled for standard operation of the breaker. It may bedesirable to include a delay line 838 (shown in phantom in FIG. 31),which provides a time delay that is sufficient to allow the mechanicalcomponents of the circuit breaker to reset before enabling AND gates 822and 824 to avoid false triggering of the circuit breaker.

Systems Having Circuit Breakers With Reset Lockout

The circuit breakers described above can be used in electricaldistribution systems in, for example, a home, shown in the exemplaryblock diagram of FIG. 32. The system includes a circuit breaker panel300 used to supply electrical power to various circuits in the home, atleast one GFCI circuit breaker having a reset lockout and/or independenttrip portions installed in the panel, and various connection points,such as receptacles, to connect one or more loads thereto. As is wellknown, the line phase connection 212 of the GFCI circuit breaker isconnected to a power distribution bus 302 in the panel and the loadphase connection 214 is connected to the phase conductor 304 feeding oneor more loads. A neutral conductor 306 to the one or more loads isconnected to a load neutral connection 218 associated with the circuitbreaker 200, and a line neutral conductor 216, typically, extending fromthe circuit breaker housing is connected to a neutral bus 308 in thepanel.

While there have been shown and described and pointed out thefundamental features of the invention, it will be understood thatvarious omissions and substitutions and changes of the form and detailsof the device described and illustrated and in its operation may be madeby those skilled in the art, without departing from the spirit of theinvention.

What is claimed:
 1. A circuit breaker comprising: a housing having aline phase connection and load phase connection accessible from anexterior of said housing; a conductive path within said housing betweensaid line and load phase connections; a circuit interrupting portiondisposed within said housing and configured to open said conductive pathupon the occurrence of a first predefined condition; a reset portionhaving an actuator extending through said exterior of said housing,wherein activation of the reset portion activates the circuitinterrupting portion, and configured to close said conductive path uponactuation of said actuator; and a reset lockout portion, responsive toactivation of the circuit interrupting portion, for preventing theclosing of said conductive path if a second predefined condition exists.2. The circuit breaker according to claim 1, wherein said firstpredefined condition includes a fault or an over-current condition. 3.The circuit breaker according to claim 2, wherein said fault includes aground fault, an arc fault, an immersion detection fault, an applianceleakage fault or an equipment leakage fault.
 4. The circuit breakeraccording to claim 1, wherein said second predefined condition includessaid circuit interrupting portion being non-operational or an openneutral condition.
 5. The circuit breaker according to claim 1, furthercomprising a trip portion disposed at least partially within saidhousing and configured to open said conductive path independently ofsaid circuit interrupting portion operation.
 6. The circuit breakeraccording to claim 5, wherein said trip portion comprises a tripactuator accessible from said exterior of said housing and a trip armcoupled to said trip actuator, said trip arm being configured tofacilitate mechanical breaking of said conductive path if said tripactuator is actuated.
 7. The circuit breaker according to claim 6,wherein said trip actuator comprises a pushbutton.
 8. The circuitbreaker according to claim 1, wherein said conductive path includes apair of contacts wherein at least one of said pair of contacts ismovable relative to the other such that said contacts can be movedbetween open and closed positions.
 9. The circuit breaker according toclaim 8, wherein said circuit interrupting portion includes sensingcircuitry used to sense the occurrence of a ground fault andelectro-mechanical linkage responsive to said sensing circuitry and usedto cause said pair of contacts to open.
 10. The circuit breakeraccording to claim 1, wherein said housing is configured and dimensionedfor installation in a circuit breaker panel.
 11. A circuit breakercomprising: a housing having line and load phase connections and lineand load neutral connections accessible from an exterior of saidhousing; a conductive path within said housing and connected betweensaid line and load phase connections; a circuit interrupting portiondisposed within said housing and configured to cause electricaldiscontinuity at a point along said conductive path upon the occurrenceof a first predefined condition; a reset portion which, upon activation,activates the circuit interrupting portion, and configured toreestablish electrical continuity in said conductive path; and a resetlockout portion, responsive to activation of the circuit interruptingportion, for preventing reestablishment of electrical continuity of saidconductive path if a second predefined condition exists.
 12. The circuitbreaker according to claim 11, wherein said first predefined conditionincludes a fault or an over-current condition.
 13. The circuit breakeraccording to claim 12, wherein said fault includes a ground fault, anarc fault, an immersion detection fault, an appliance leakage fault oran equipment leakage fault.
 14. The circuit breaker according to claim11, wherein said second predefined condition includes said circuitinterrupting portion being non-operational, or an open neutralcondition.
 15. The circuit breaker according to claim 11, furthercomprising a trip portion having a trip actuator extending through saidhousing and configured to activate a trip operation causing electricaldiscontinuity in said conductive path in response to said trip actuatorbeing manually actuated, said trip operation being independent of saidcircuit interrupting portion operation.
 16. The circuit breakeraccording to claim 15, wherein said trip actuator comprises apushbutton.
 17. The circuit breaker according to claim 15, wherein saidtrip operation mechanically causes electrical discontinuity along saidconductive path.
 18. The circuit breaker according to claim 17, whereinsaid trip portion further comprises a trip arm coupled to said tripactuator that mechanically causes said electrical discontinuity alongsaid conductive path.
 19. The circuit breaker according to claim 11,wherein said circuit interrupting portion includes sensing circuitryused to sense the occurrence of a ground fault and electro-mechanicallinkage responsive to said sensing circuitry and used to cause saidelectrical discontinuity.
 20. The circuit breaker according to claim 19,wherein said reset portion comprises: a manually operated actuatoroperatively coupled to said reset lockout; and a reset enable switchassembly electrically connected to said sensing circuitry, which iscapable of being activated by operation of said actuator, such thatactuation of said reset enable switch assembly simulates a ground faultin said sensing circuitry so as to activate said circuit interruptingportion.
 21. The circuit breaker according to claim 20, wherein saidreset enable switch assembly comprises a fixed contact that is energizedby said operation of said actuator to simulate the ground fault.
 22. Thecircuit breaker according to claim 20, wherein said reset enable switchassembly comprises a pair of momentary switches which when actuatedswitch power supplied to said sensing circuitry from said load phaseconnection to said line phase connection, and simulate the ground fault.23. The circuit breaker according to claim 20, wherein said reset enableswitch assembly comprises a plurality of switch contacts that aresequentially activated to first switch power supplied to said sensingcircuitry from said load phase connection to said line phase connection,and second to simulate the ground fault.
 24. A GFCI circuit breakercomprising: a housing; a pair of input conductors, one of said pairbeing a phase conductor and the other being a neutral conductor, saidconductors being disposed within said housing and terminating through anexterior surface of said housing; a pair of output conductors, one ofsaid pair being a phase conductor and the other being a neutralconductor, said conductors being disposed within said housing andterminating through an exterior surface of said housing, wherein saidinput phase conductor is connectable to said output phase conductor suchthat electrical continuity exists between said input and output phaseconductors; a circuit interrupting portion disposed within said housingand configured to break the continuity between said input phaseconductor and said output phase conductor upon the occurrence of aground fault; a reset portion which, upon activation, activates thecircuit interrupting portion, and configured to make electricalcontinuity between said input phase conductor and said output phaseconductor after a ground fault occurs; and a reset lockout, responsiveto activation of the circuit interrupting portion, for preventing themaking of electrical continuity between said input phase conductor andsaid output phase conductor if a predetermined condition exists.
 25. TheGFCI circuit breaker according to claim 24, further comprising a tripmechanism disposed at least partially within said housing and configuredto break the continuity between said input phase conductor and saidoutput phase conductor independently of said circuit interruptingportion operation.
 26. The GFCI circuit breaker according to claim 25,wherein said trip mechanism comprises a trip actuator accessible fromsaid exterior surface of said housing and a trip arm extending from saidtrip actuator, said trip arm being configured to facilitate mechanicalbreaking of electrical continuity between said input phase conductor andsaid output phase conductor upon actuation of said trip actuator. 27.The GFCI circuit breaker according to claim 26, wherein said tripactuator comprises a pushbutton.
 28. The GFCI circuit breaker accordingto claim 24, wherein said predetermined condition includes said circuitinterrupting portion being non-operational or an open neutral condition.29. An AFCI circuit breaker comprising: a housing; a pair of inputconductors, one of said pair being a phase conductor and the other beinga neutral conductor, said conductors being disposed within said housingand terminating through an exterior surface of said housing; a pair ofoutput conductors, one of said pair being a phase conductor and theother being a neutral conductor, said conductors being disposed withinsaid housing and terminating through an exterior surface of saidhousing, wherein said input phase conductor is connectable to saidoutput phase conductor such that electrical continuity exists betweensaid input and output phase conductors; a circuit interrupting portiondisposed within said housing and configured to break the continuitybetween said input phase conductor and said output phase conductor uponthe occurrence of an arc fault; a reset portion which, upon activation,activates the circuit interrupting portion, and configured to makeelectrical continuity between said input phase conductor and said outputphase conductor after an arc fault occurs; and a reset lockout,responsive to activation of the circuit interrupting portion, forpreventing the making of electrical continuity between said input phaseconductor and said output phase conductor if a predetermined conditionexists.
 30. The AFCI circuit breaker according to claim 29, furthercomprising a trip mechanism disposed at least partially within saidhousing and configured to break the continuity between said input phaseconductor and said output phase conductor independently of said circuitinterrupting portion operation.
 31. The AFCI circuit breaker accordingto claim 30, wherein said trip mechanism comprises a trip actuatoraccessible from said exterior surface of said housing and a trip armextending from said trip actuator, said trip arm being configured tofacilitate mechanical breaking of electrical continuity between saidinput phase conductor and said output phase conductor upon actuation ofsaid trip actuator.
 32. The AFCI circuit breaker according to claim 31,wherein said trip actuator comprises a pushbutton.
 33. The AFCI circuitbreaker according to claim 29, wherein said predetermined conditionincludes said circuit interrupting portion being non-operational or anopen neutral condition.
 34. A circuit breaker comprising: a housinghaving a line phase connection and load phase connection accessible froman exterior of said housing; a conductive path within said housingbetween said line and load phase connections; a circuit interruptingportion disposed within said housing and configured to open saidconductive path upon the occurrence of at least one of a plurality ofpredefined conditions; a reset portion having an actuator extendingthrough said exterior of said housing, wherein activation of the resetportion activates the circuit interrupting portion, and configured toclose said conductive path upon actuation of said actuator; and a resetlockout portion, responsive to activation of the circuit interruptingportion, for preventing the closing of said conductive path if a secondpredefined condition exists.
 35. The circuit breaker according to claim34, wherein said plurality of predefined conditions include groundfaults, arc faults, immersion detection faults, appliance leakage faultsand equipment leakage faults.
 36. The circuit breaker according to claim34, wherein said second predefined condition includes said circuitinterrupting portion being non-operational or an open neutral condition.37. The circuit breaker according to claim 34, further comprising a tripportion disposed at least partially within said housing and configuredto open said conductive path independently of said circuit interruptingportion operation.
 38. The circuit breaker according to claim 37,wherein said trip portion comprises a trip actuator accessible from saidexterior of said housing and a trip arm coupled to said trip actuator,said trip arm being configured to facilitate mechanical breaking of saidconductive path if said trip actuator is actuated.
 39. The circuitbreaker according to claim 38, wherein said trip actuator comprises apushbutton.
 40. The circuit breaker according to claim 34, wherein saidconductive path includes a pair of contacts wherein at least one of saidpair of contacts is movable relative to the other such that saidcontacts can be moved between open and closed positions.
 41. The circuitbreaker according to claim 40, wherein said circuit interrupting portionincludes sensing circuitry used to sense the occurrence of saidplurality of predefined conditions and electro-mechanical linkageresponsive to said sensing circuitry and used to cause said pair ofcontacts to open.
 42. The circuit breaker according to claim 34, whereinsaid circuit interrupting portion comprises sensing circuitry used tosense the occurrence of said plurality of predefined conditions; andwherein said reset portion comprises a fault simulator electricallyconnected to said sensing circuitry and capable of being activated bysaid actuator, such that activation of said fault simulator simulatesone or more of said plurality of predefined conditions causing saidsensing circuitry to sense the occurrence of said one or more of saidplurality of predefined conditions.
 43. The circuit breaker according toclaim 42, wherein said plurality of predefined conditions includesground faults, arc faults, immersion detection faults, appliance leakagefaults and equipment leakage faults.
 44. The circuit breaker accordingto claim 43, wherein said one or more of said plurality of predefinedconditions comprise a ground fault and an arc fault.
 45. The circuitbreaker according to claim 43, wherein said one or more of saidplurality of predefined conditions comprise a ground fault.
 46. Thecircuit breaker according to claim 43, wherein said one or more of saidplurality of predefined conditions comprise an arc fault.
 47. Thecircuit breaker according to claim 34, wherein said housing isconfigured and dimensioned for installation in a circuit breaker panel.